Shown with a cast-on count of 13 stitches.  

• Rows 1, 3, 5, 7, and 9 (RS): *K2tog, k2, incR, k2, repeat from * to last st, k1.
• Rows 2, 4, 6, 8, and 10: *P2tog, p2, incL, p2, repeat from * to last st, p1.
• Row 11: *K2tog, k1, (k1, yo, k1) in next st, k2, repeat from * to last st, k1 (multiple of 7 sts, plus 1).
• Row 12: *P2tog, p2, (p1, yo, p1) in next st, p2, repeat from * to last st, p1 (multiple of 8 sts, plus 1).
• Row 13: *K2tog, k2, (k1, yo, k1) in next st, k3, repeat from * to last st, k1 (multiple of 9 sts, plus 1).
• Row 14: *P2tog, p3, (p1, yo, p1) in next st, p3, repeat from * to last st, p1 (multiple of 10 sts, plus 1).
• Row 15: *K2tog, k3, (k1, yo, k1) in next st, k4, repeat from * to last st, k1 (multiple of 11 sts, plus 1).
• Row 16: *P2tog, p4, (p1, yo, p1) in next st, p4, repeat from * to last st, p1 (multiple of 12 sts, plus 1).
• Row 17: *K2tog, k4, (k1, yo, k1) in next st, k5, repeat from * to last st, k1 (multiple of 13 sts, plus 1).
• Row 18: *P2tog, p5, (p1, yo, p1) in next st, p5, repeat from * to last st, p1 (multiple of 14 sts, plus 1).
• Row 19: *K2tog, k5, (k1, yo, k1) in next st, k6, repeat from * to last st, k1 (multiple of 15 sts, plus 1).
• Row 20: *P2tog, p6, (p1, yo, p1) in next st, p6, repeat from * to last st, p1 (multiple of 16 sts, plus 1).